ICP DAS USA I-7021 User Manual

Also see for M-7024: Quick start guide

Contents

ICP DAS USA I-7021 User Manual Manual pdf 153 page image

I-7021/22/24, M-7022/24/28 User Manual, Rev: B2.3 1533. Modbus RTU ProtocolThe Modbus protocol is developed by Modicon Inc., originallydeveloped for Modicon controllers. Detailed information can befound at http://www.modicon.com/techpubs/toc7.html. You canalso visit http://www.modbus.org to find more valuableinformation.M-7000 series modules support the Modbus RTU protocol. Thecommunication Baud Rates range from 1200bps to 115200bps.The number of data bits is fixed to 8. For M-7022 firmwareversion B102 and later, M-7024 firmware version B202 and later,M-7024L, M-7024R, M-7024U and M-7028, the parity can benone, even or odd. For M-7022 other versions and M-7024 otherversions, the parity and stop bits are fixed as no parity and 1 stopbit. The following Modbus functions are supported.Function Code Description Section01 (0x01) Read coils 3.102 (0x02) Read digital inputs 3.203 (0x03) Read output channels 3.304 (0x04) Read input channels 3.405 (0x05) Write single coil 3.506 (0x06) Write single register 3.615 (0x0F) Write multiple coils 3.716 (0x10) Write multiple registers 3.8If the function specified in the message is not supported, then themodule responds as follows.Error Response00 Address 1 Byte 1 to 24701 Function code 1 Byte Function code | 0x8002 Exception code 1 Byte 01If a CRC mismatch occurs, the module will not respond.